Dynamo-electric machine.



s. H. MURRAYJR. DYNAMO ELECTRIC MACHINE,- APPLICATION FILED NOV- 6,1914.

Mama Feb. 5, 1918."

1 INIENTOR GeargeHMur/"ay J1:

-f 4. I ATTGHNEY UNITED. STATES PATENT caries GEORGE H. MURRAY, JR,OFWILKINSBURG, PENNSYLVANIA, ASSIGNOB; TO WESTING- HOUSE ELECTRICAND-MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- VANIA.

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v Specifieationof Letters Patent.

Patented Feb. 5, 1918.

To all whom it may concern:

Be it known that I, GEORGE H. MURRAY, Jr., a citizen of the UnitedStates, and a resident of VVilkinsburg, in the county of Allegheny andState of Pennsylvania, have invented a new and useful Improvement inDynamo-Electric Machines, of which the following is a specification.

My invention relates to amortisseur windings for dynamo-electricmachines, and it has for its object to provide a winding of thecharacter specified that shall be simple and effective, and havesufficient strength to withstand severe mechanical stresses imposedthereon when placed on the rotatingfield members of alternating currentmachines of large capacity. I

In the design and construction of alternating current machines ofvarious types, it has been found desirable to provide the field magnetswith short circuited windings of the squirrel-cage or grid type, inorder that the currents induced therein may exercise a beneficial effectin the operation of the machine. Such windings are termed amortisseur ordamper windings and are commonly used on synchronous apparatus toprevent hunt ing or to provide means for starting such apparatus bymeans of the torque produced by induction-motor action in the shortcircuited windings.

Amortisseur windings, as heretofore constructed, comprised a number ofconducting bars embedded in each field magnet core and connected, attheir ends, by suitable short circuiting rings. This construction, whileeffective for all electrical purposes, possesses a disadvantage in thatthe overhung portions of the embedded bars and the unsupported end ringsattached thereto are liable to failure when subjected to severemechanical stresses.

Stresses caused by centrifugal force occur in the rotating field membersof certain types of synchronous apparatus of large capacity whendesigned to operate at momentary excessiVe overspeeds, such as mightoccur in the operation of synchronous motors used for transmission lineregulation. For such machines, the ordinary open-grid type ofamortisseur winding would be undesirable because of the large bendingmoments that would be produced by centrifugal stresses in the end ringsupon the overhanging portions of the conducting bars.

By my invention, I propose to construct a completely embeddedamortisseur winding that shall be supported at all points and so form arigid structure capable of withstand ing' severe mechanical stresses.

In the accompanying drawings, Figure 1 is an end view, partially insection and partially in elevation, of a portion of a rotating fieldmember of a dynamo-electric machine provided with an amortisseur windingconstructed in accordance with my invem tion; Fig. 2 is a sectional viewtaken on the line IIII of Fig. 1, and Fig. 3 is a. fragmentary plan viewof the parts shown in Fig. 1.

A field magnet yoke 1 carries magnet pole pieces2 which are built up oflaminations 3 and end plates 4 bolted and dove-tailed to the yoke 1, inthe usual manner. Partially closed slots 5, extending through thecorelamin ations 3, contain brass or copper bars 6'which extend beyond theends of the slots 5 at both ends. The end plates at are provided withgrooves 7 that are adapted to receive the projecting portions 8 of thebars 6. The grooves 7 are cut to conform to the curvature of the corelaminations 3 and are of suflicient depth to allow a curved segment 9 ofthe same material as the bars 6 to extend beneath the projectingportions 8. Set screws 10 secure the segments 9 to the bars to form arigid self-bracing structure on each field magnet core.

The segments 9 extend equal distances beyond the edges of the end plates4:, and adjacent segments are connected, in a well known manner, by theuse of joint members 12 that are secured to oppositely disposed cut awayportions 11 by bolts 13 and nuts 14:. It is to be understood that anyother suitable connecting means may be used in forming a closed circuitbetween adjacent segments.

The amortisseur winding is thus formed of a number of groups of embeddedconductors which are so arranged with respect to each other thatcentrifugal stresses set up in the segments 9 do not produce excessivebending moments upon the projecting portions 8 of the conducting bars 6.Thus, a complete winding, constructed according to my invention, isrendered incapable of any distortion tending to destroy itsefiectiveness as an electrical device.

WhllQ I have shown my invention in its simplest and preferred form, itis not so limited, but is capable of various modifications within thescope of the appended claims.

I claim as my invention:

1. An amortisseur winding for dynamoelectric machines comprising aplurality of groups of electric conductors, each of said groupsconsisting of a plurality of parallel conductors embedded in the core ofa field magnet, and a pair of similarly embedded conductors extending atright angles to, and located directly beneath the ends of, said parallelconductors and connected thereto, and means for connecting said groupsof embedded conductc-rs to form a closed electric circuit.

2. In the field magnet structure of a dynamo-electric machine, thecombination with a magnetcore provided with a plurality of parallelslots and other slots at right angles to said parallel slots, of aplurality of electric conductors carried in said slots, certain of saidconductors having portions thereof superimposed upon the others, andmeans for connecting said conductors to form a closed electric circuit.

3. In the field magnet structure of a dynamo-electric machine, thecombination with a plurality of magnet cores, each of said cores beingprovided with a pair of slots adjacent to the ends of said core and aplurality of parallel slots at right angles to, and

opening into, said first named slots, of a plurality of electricconductors carried in said parallel slots and projecting into said firstnamed slots, a plurality of similar conductors carried in said firstnamed slots beneath the projecting portions of said parallel conductors,and means for connecting said slot-contained conductors to form a closedelectric circuit.

a. In the field magnet structure of a dynamo-electric machine, thecombination with a plurality of magnet cores, each of said cores beingprovided with a pair of open slots adjacent to the ends of said core anda plurality of partially closed parallel slots at right angles to, andterminating in, said open slots, of plurality of electric conductorscarried in said parallel slots and projecting into said open slots, aplurality of similar conductors carried at the bottoms of said openslots directly beneath the projecting portions of said parallelconductors, and means for connecting said slot-contained conductors toform a closed electric circuit.

In testimony whereof, I have hereunto subscribed my name this 29th dayof Oct, 1914.

GEO. H. MURRAY, JR.

Witnesses:

EMIL MOTTMAN, B. B. HINES.

Copies 01' this patent may be obtained for five cents each. byaddressing the Commissioner of Patents,

Washington, I). C.

